Process of obtaining magnesia.



LIA. BRADBURN.

Y PROCESS OF OBTAINING MAGNESIA.

APPLICATION FILED NOV. 28, 1914.

WITNESSES I INVESTOR fiagmfljrzflaow j; 6 it :ZZ By m 0ct.12,1915.

ATTORNEYS Obtaining Magnesia, of

JOSEPH A. BBADBURN, OF SYRACUSE," NEW YORK.

PROCESS OF OBTAINING MAGNESIA. I

To all whom it may concern:

Be it known that I, JosnrH A. BRADBURN,

a citizen of the United States, and a resident of Syracuse, in the county of Onondaga and State of New York, have made certain new and useful Improvements in Processes of which the followin is a specification.

y invention relates to improvements in methods or processes of obtaining magnesia from dolomite or dolomitic limestone, and it consists in the various steps hereinafter enumerated and particularly pointed out in the appended claims.

An object of my invention is to provide a process by means of which magnesia may be roduced.

economically A further 0 Ject of my'invention is to pro-' vide a process which will roduce a relatively pure magnesia, in t at it does not contain other deleterious; substances.

Other objects and advantages will appear in the following specification, and the novel features ofthe invention will be particularl pointed out in the appended claims.

y invention is illustrated in the accom panying drawings forming part of this application in which Fi re lis a section through a tank which may e used with this process, and Fig. '2 is a section along the line 22 of Fig. 1.

It will be understood that the drawings are merely for explaining the process, but that the process is not at all dependent upon any particular form of ap be carried-out by any suita 1e apparatus.

The raw material, as stated above, is dolomite a natural double carbonateof calcium and magnesium or dolomitic limestone. This is first calcined atiajytcmperature not higher than is necessary to'decompose the calcium carbonate and themagnesium carbonate. .The calcined "material is then placed in a tank, such as the A shown in the drawings, and water is added. The mixture is then'stirred with a stirrer, such as that shown at B, which maybe operated by any suitable power, as'by drive pulleys C and belt D. This stirrer is kept in motion so as to keep the solid and liquid parts of the milk, which is formed, thoroughly mixed. The mixture is kept in the tank from one to three days or long enough to secure a sufliciently complete hydration of the dolomitic calcium and magnesium GaH O MgH O It the temperature of Specification of Letters Patent.

land a residual liquor containin aratus but may,

Patented Oct. 12, 1915.

Application filed November 28, 1914. Serial No. 874,424.

calcination is kept about 800 C; the product Wlll be practically hydrated in twenty-two to seventy-four hours. The dolomitic milk, thus prepared'is mixed with a solution of sodium and ammonium chlorids, NaCl AmCl containing in one liter about to 90 grams NaCl and about 120 to 180 grams AmCl. A liquor 5 of this'combination is made in the manufacture of soda by the ammonia process. Such a quantity of this solution is used as will convert the .CaH O MgH O of the dolomitic milk to CaCl :MgCl and leave some AmCl unchanged.

The latter is then distilled in a suitable apparatus to obtain the liberated ammonia which may be used for any suitable purpose calclum chlorid, magnesium chlorid. an sodium nesium shall be converted'to calciumchlorid and magnesium chlorid, then near the end of thedistillation enough of the milk of calcine'd dolomite is added to decompose the remaining ammonium chlorid and the distillation is continued until the liquor is free from ammonia. v

,The residual liquor from the distillation ,Which contains calcium chlorid, magnesium chlorid and sodium chlorid'is settled or filtered to obtain a clear liquor; To this liquor added either a milk of calcined;dolomite :'.-,which may be completely hydrated or not,

contain suflicient CaO or CaH,O to decompose the magnesium chlorid present and precipitate its magnesium in the form of magnesium hydrate (MgH' ml without introducing an unnecessary excess of lime. The magnesium oxid in the added calcined dolomite does not ,enter'into the reaction but is also precipitated; with the magnesium hydrate coming from the magnesium chlorid. During the recipitation the liquor is. heated and agitated The following represents the chemical reactions:

The liquid with its precipitate is caused to flow through a settling tankor a series of settling tanks in which the comparatively heavy magnesium oxid collects near sium hydrate is filtered out of the liquor, then washed free from magnesium chlorid and sodium chlorid, after which it may be dried and used for any suitable purpose.

The magnesium oxid is also collected out of the liquor by a filter or otherwise (by running out the liquor from near the inlet of the tank) then Washed free from the chloride of calcium and sodium, after which it may be dried and used for any suitable purpose. Magnesia is obtained by calcining the magnesium hydrate.

As a modification of the process. the milk of calcined dolomite before going through the hydrating tanks. may be at once mixed with the sodium chlorid and ammonium chlorid liquor and the whole either passed through the distilling operation or first passed through the hydrating tanks and thence to the distilling operation.

A further modification is to take thedry powdered calcined dolomite and add it to the sodium chlorid ammonium chlorid liquor and then pass the latter directly to the distilling operation or first through the hydrating tanks and thence to the distilling operation.

I claim 1. The herein described process of producing magnesia from a dolomitic substance containing carbonate of calcium and mag nesium, which consists in calcining said sub stances at a temperature not higher than necessary to decompose the calcium carbonate pared with a solution of sodium and"'ammonium chlorids, distilling, the solution thus treated to free the same from ammonia, treating the residual solution with calcined dolomite whereby magnesium hydrate is precipitated from the solution and mag nesium oxid is separated from the calcined dolomite, collecting'the magnesium hydrate and the magnesium oxid each separately from the liquor, and calcining the magnesium hydrate.

2. The herein described process of pro ducing magnesia from a dolomitic substance containing carbonate of calcium and magnesium, which consists in calcining said substances, treating the calcined product with water to hydrate the same, mixing the hydrated solution with a solution of sodium and ammonium chlorids, distilling the solution to free the same from ammonia, treating the residual solution with calcined dolo- -mite whereby magnesium hydrate is precipitated from the solution and magnesium oxid is separated from the calcined dolomite, collecting the magnesium hydrate'and the magnesium oxid each separately from the liquor, and calcining the magnesium hydrate;

3. The herein described step in the process of producing magnesia from a dolomitic 'substan e'e, which consists in treating cal- W itnesses C. W. ANNABLE, A. ANNABLE'. 

